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Experiment to Determine the Coefficient of Friction

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Student Name: Ahmad Raza

Summary:

This experiment has two aims. The first aim of this experiment is to determine the coefficient of friction on an inclined plane by using various materials tray. Secondly, to verify that the force have already found which were required to move a body on an inclined plane. We have provided apparatus to do this experiment that include stainless steel plane, load hanger, different weights and 4 trays of different materials such as aluminium, brass, nylon and ferado. Firstly, we place tray at the middle of plane and apply weight on weight hanger until tray starts to move. Note the angle and find the coefficient of friction. For this purpose we have found the Normal force and sliding. Then, by using formula of coefficient of friction we found the value, which was approximately 0.18 at 10°, 20° and 30°. Nevertheless, the additional 10N weight was added but the friction coefficient but the angle will remain same. The experiment was taken by under good circumstances. However, errors can be reduce by overlapping the mistake that was take place in this experiment. This experiment could be done exactly the same as international standard if the following conditions apply on it.

CHAPTER 1 INTRODUCTION

  1. AIMS AND OBJECTIVE

The aims of the friction experiment are to find the coefficient of different combination of material which is in this experiment, the steel bar. Making use of inclined plane, also to study equilibrium and non-equilibrium of a body of an incline plane under the action of the force. The objective is to understand that a coefficient of friction could be determine via incline plane, collect experiment data and calculate the corresponding results and coefficient and finally to compare the value of coefficient generated from different pairs of surface.

1.2: THEORY AND BACKGROUND:

Friction can be defined as the force that will resists the relative motion of solid surfaces which are sliding against each other. There are mainly three types of friction. Dry friction, Fluid friction and internal friction but this particular experiment was just examined only for dry friction. Dry friction is the encountered when two dry surfaces are in convention if there is a tendency of sliding. However this dry friction has split into two sub frictions as static and kinetic. Commonly, kinetic frictional force will be less than the absolute maximum value from the static frictional force. This static frictional force is derived as fs = μsN, while kinetic frictional force is fk =μkN, where μs is the coefficient of static friction, μk is the coefficient of kinetic friction, N is the normal force and μ is the proportionality constant and called coefficient of friction.

An inclined plane can be defined as any plane surface positioned at an angle with respect to the horizontal plane. At the moment of sliding, the friction force must be the same to the element of weight acting down the plane.

 

μW .cosθ =W .sinθ

This leads to the concept of the angle of the friction

μ = tanθ

CHAPTER 2 APPRATUS AND experimental procedure

2.1: APPRATUS:

  • Adjustable stainless steel plane complete with base
  • .5N load hanger
  • Weights
  • Trays of Aluminium, Brass, Nylon and Ferado

Fig1.1: Wood plane and trays

2.2: experimental procedure:

As we discussed above, we have two aims for this experiment. Each aim has different procedure.

2.2.1: Following procedure is to find the angle of friction on a steel plane by using different materials. We have given four trays for this experiment such as Aluminium, Brass, Nylon and Ferado. First of all set the plane of stainless steel at 0 slope by ensuring that it is in horizontal plane. Afterward, set the tray of any material at the middle of stainless steel plane then apply weight at the end of plane by weight hanger and note the angle of inclination when tray starts to slide. Take coefficient of Tan θ to evaluate static deflection (μs).Repeat the same procedure three times and take the average. Subsequently, to evaluate the angle of sliding friction (μk) , place the tray again in the middle of plane and reduce the tilt as this time tilt was increased, we keep pushing the tray till it started to move and note the angle for three times and take the average.

Static deflection (μs)

  • Measure angle θ for static deflection by using Aluminium tray

Table 1.1: Aluminium tray

1st θ

2nd θ

3rd θ

Average

18.5

16

13

15.8

  • Measure angle θ for static deflection by using Brass tray

Table 1.2: Brass tray

1st θ

2nd θ

3rd θ

Average

13

14

15

14

  • Measure angle θ for static deflection by using Nylon tray

Table 1.3: Nylon tray

1st θ

2nd θ

3rd θ

Average

17.5

19.5

23

20

  • Measure angle θ for static deflection by using Ferado tray

Table 1.4: Ferado tray

1st θ

2nd θ

3rd θ

Average

20

19.5

17

18.8

Sliding Friction (μk)

  • Measure angle θ for sliding friction by using Aluminium tray

Table 2.1: Aluminium tray

1st θ

2nd θ

3rd θ

Average

11

10.5

11

10.8

  • Measure angle θ for sliding friction by using Brass tray

Table 2.2: Brass tray

1st θ

2nd θ

3rd θ

Average

15

15

15.5

15.1

  • Measure angle θ for sliding friction by using Nylon tray

Table 2.3: Nylon tray

1st θ

2nd θ

3rd θ

Average

12.5

12

12.5

12.3

  • Measure angle θ for sliding friction by using Ferado tray

Table 2.4: Ferado tray

1st θ

2nd θ

3rd θ

Average

13.5

14

13.5

13.7

2.2.2: Following procedure is to verify the force required parallel to an inclined plane to move a body up the plane corresponds to the friction coefficient already found. First of all set the stainless steel plane horizontally at 10 slope. Place the towing cord and weight hanger in position to pull the tray up to the plane by placing any material tray at the lower end of plane. Add load to the hanger until the tray, given a slide push, slides slowly up the plane. Repeat the same procedure by applying 10N weight at angle 20 and 30.

CHAPTER 3 CALCULATIONS AND RESULTS

3.1: Procedure 1

  • As we found angle above, now to find coefficient of static deflection, take tan θ.

For Aluminium (Tan15.8) = 0.28

For Brass (Tan14) = 0.25

For Nylon (Tan20) = 0.36

For Ferado (Tan18.8) = 0.34

Table 3.1: Coefficient of static deflection

Material

Angle θ

Coefficient

Tan θ

Aluminium

15.8

0.28

Brass

14

0.25

Nylon

20

0.36

Ferado

18.8

0.34

  • As we found angle above, now to find the coefficient of sliding friction, take tan θ.

For Aluminium (Tan10.8) = 0.19

For Brass (Tan15.1) = 0.27

For Nylon (Tan12.3) = 0.22

For Ferado (Tan13.7) = 0.24

Table 3.1: Coefficient of sliding friction

Material

Angle θ

Coefficient

Tan θ

Aluminium

10.8

0.19

Brass

15.1

0.27

Nylon

12.3

0.22

Ferado

13.7

0.24

Procedure 2:

  • First of all find the normal force

Normal Force = W.cosθ

Normal Force = 3.58.cos10°

Normal Force = 3.52 N

  • Secondly find the Sliding force

Sliding Force = p-(W.sinθ)

Sliding Force = 1.2-(3.58.sin10°)

Sliding Force = 0.58 N

  • Now as we have both normal and sliding force, we can find Friction Coefficient μ

Friction Coefficient = Sliding force / Normal force

Friction Coefficient = 0.58 / 3.52

Friction Coefficient = 0.16

  • All the values were measured for angle 20° and 30° as shown in the table below.

Table 4.1:

Angle of plane

θ

Towing

Force (p)

N

Weight of tray (W)

N

Normal force

W.cosθ

N

Sliding force

p-(W.sinθ)

N

Friction

Coefficient

μ

Friction angle

tan−1

10°

1.2

3.58

3.52

0.58

0.16

9.09

20°

1.85

3.58

3.36

0.62

0.18

10.2

30°

2.35

3.58

3.1

0.56

0.18

10.2

10°

4.95

13.58

13.37

2.59

0.19

10.75

20°

6.9

13.58

12.76

2.25

0.18

10.2

30°

8.95

13.58

11.76

2.16

0.18

10.2

Nevertheless, the additional 10N weight were added but the friction coefficient and angle will remain same as shown above in the table which proves that weight cannot change the angle and coefficient of friction.

By converting mass of the tray into weight we can prove the experiment.

W = mg

W = 0.365*9.81

W = 3.58 N

CHAPTER 4 ANALYSIS AND DISCUSSION

Subsequently investigation in the data, we all observed that hypothesis is true, where the static along with kinetic friction is usually affected by the mass of body. The coefficient in the kinetic along with static friction is determined by materials used for each call surfaces. The coefficients will never always be bigger than 1 and the coefficient connected with kinetic friction is definitely more compact as opposed to among static friction for that identical scenario. The value of coefficient of friction is 0.18.The laboratory on the other hand, we all would come up with a vibrant mistake that's produced each of our kinetic friction importance unfeasible, as the importance for we all received ended up being caused by the tension pulling on the block.

However, there were some systematic error occur while doing experiment. These errors were arisen due to string and hanger as they were not straight and each group member have different value while taking reading.

CHAPTER 5 CONCLUSION

The experiment was taken under good circumstances. However, errors can be reduce by overlapping the mistake that was take place in this experiment. This experiment could be done exactly the same as international standard if the following conditions apply on it. First of all make sure that the hanging masses do not move while adding additional weight on load hanger. This experiment will be really useful in the future to determine the coefficient of friction for different materials.

REFERENCE:

John, B Carl,T.F.T.F. Ross (2002).Mechanical Engineering Principles. Oxford: Taylor & Francis.

APPENDIX A

CHAPTER 1........................................................... CHAPTER 2........................................................... CHPATER 3........................................................... CHAPTER 4..........................................................

 

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